A laboratory study of anisotropic geomaterials incorporating recent micromechanical understanding

This paper presents an experimental investigation revisiting the anisotropic stress–strain–strength behaviour of geomaterials in drained monotonic shear using hollow cylinder apparatus. The test programme has been designed to cover the effect of material anisotropy, preshearing, material density and...

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Main Authors: Yang, L.-T., Li, X., Yu, Hai-Sui, Wanatowski, D.
Format: Article
Published: Springer Verlag 2016
Subjects:
Online Access:https://eprints.nottingham.ac.uk/47490/
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author Yang, L.-T.
Li, X.
Yu, Hai-Sui
Wanatowski, D.
author_facet Yang, L.-T.
Li, X.
Yu, Hai-Sui
Wanatowski, D.
author_sort Yang, L.-T.
building Nottingham Research Data Repository
collection Online Access
description This paper presents an experimental investigation revisiting the anisotropic stress–strain–strength behaviour of geomaterials in drained monotonic shear using hollow cylinder apparatus. The test programme has been designed to cover the effect of material anisotropy, preshearing, material density and intermediate principal stress on the behaviour of Leighton Buzzard sand. Experiments have also been performed on glass beads to understand the effect of particle shape. This paper explains phenomenological observations based on recently acquired understanding in micromechanics, with attention focused on strength anisotropy and deformation non-coaxiality, i.e. non-coincidence between the principal stress direction and the principal strain rate direction. The test results demonstrate that the effects of initial anisotropy produced during sample preparation are significant. The stress–strain–strength behaviour of the specimen shows strong dependence on the principal stress direction. Preloading history, material density and particle shape are also found to be influential. In particular, it was found that non-coaxiality is more significant in presheared specimens. The observations on the strength anisotropy and deformation non-coaxiality were explained based on the stress–force–fabric relationship. It was observed that intermediate principal stress parameter b(b = (σ2 − σ3)/(σ1 − σ3)) has a significant effect on the non-coaxiality of sand. The lower the b-value, the higher the degree of non-coaxiality is induced. Visual inspection of shear band formed at the end of HCA testing has also been presented. The inclinations of the shear bands at different loading directions can be predicted well by taking account of the relative direction of the mobilized planes to the bedding plane.
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spelling nottingham-474902020-05-04T18:14:54Z https://eprints.nottingham.ac.uk/47490/ A laboratory study of anisotropic geomaterials incorporating recent micromechanical understanding Yang, L.-T. Li, X. Yu, Hai-Sui Wanatowski, D. This paper presents an experimental investigation revisiting the anisotropic stress–strain–strength behaviour of geomaterials in drained monotonic shear using hollow cylinder apparatus. The test programme has been designed to cover the effect of material anisotropy, preshearing, material density and intermediate principal stress on the behaviour of Leighton Buzzard sand. Experiments have also been performed on glass beads to understand the effect of particle shape. This paper explains phenomenological observations based on recently acquired understanding in micromechanics, with attention focused on strength anisotropy and deformation non-coaxiality, i.e. non-coincidence between the principal stress direction and the principal strain rate direction. The test results demonstrate that the effects of initial anisotropy produced during sample preparation are significant. The stress–strain–strength behaviour of the specimen shows strong dependence on the principal stress direction. Preloading history, material density and particle shape are also found to be influential. In particular, it was found that non-coaxiality is more significant in presheared specimens. The observations on the strength anisotropy and deformation non-coaxiality were explained based on the stress–force–fabric relationship. It was observed that intermediate principal stress parameter b(b = (σ2 − σ3)/(σ1 − σ3)) has a significant effect on the non-coaxiality of sand. The lower the b-value, the higher the degree of non-coaxiality is induced. Visual inspection of shear band formed at the end of HCA testing has also been presented. The inclinations of the shear bands at different loading directions can be predicted well by taking account of the relative direction of the mobilized planes to the bedding plane. Springer Verlag 2016-10-31 Article PeerReviewed Yang, L.-T., Li, X., Yu, Hai-Sui and Wanatowski, D. (2016) A laboratory study of anisotropic geomaterials incorporating recent micromechanical understanding. Acta Geotechnica, 11 (5). pp. 1111-1129. ISSN 1861-1133 Anisotropy; Discrete elements; Laboratory tests; Numerical models; Plasticity; Sand (soil type) https://doi.org/10.1007/s11440-015-0423-7 doi:10.1007/s11440-015-0423-7 doi:10.1007/s11440-015-0423-7
spellingShingle Anisotropy; Discrete elements; Laboratory tests; Numerical models; Plasticity; Sand (soil type)
Yang, L.-T.
Li, X.
Yu, Hai-Sui
Wanatowski, D.
A laboratory study of anisotropic geomaterials incorporating recent micromechanical understanding
title A laboratory study of anisotropic geomaterials incorporating recent micromechanical understanding
title_full A laboratory study of anisotropic geomaterials incorporating recent micromechanical understanding
title_fullStr A laboratory study of anisotropic geomaterials incorporating recent micromechanical understanding
title_full_unstemmed A laboratory study of anisotropic geomaterials incorporating recent micromechanical understanding
title_short A laboratory study of anisotropic geomaterials incorporating recent micromechanical understanding
title_sort laboratory study of anisotropic geomaterials incorporating recent micromechanical understanding
topic Anisotropy; Discrete elements; Laboratory tests; Numerical models; Plasticity; Sand (soil type)
url https://eprints.nottingham.ac.uk/47490/
https://eprints.nottingham.ac.uk/47490/
https://eprints.nottingham.ac.uk/47490/